Uncovering the centrality of mono-dentate SO₃^2-/SO₄^2- modifiers grafted on a metal vanadate in accelerating wet NO_X reduction and poison pyrolysis

NO_X rarely binds with labile oxygens of catalytic solids, whose Lewis acidic (LA) species possess higher binding strengths with NH₃ (E_NH3) and H₂O than Brönsted acidic counterparts (BA^--H⁺; -OH), oftentimes leading to elevate energy barrier (E_BARRIER) and weaken H₂O tolerance, respectively. These limit NH₃-assisted wet NO_X reduction via Langmuir-Hinshelwood-type or Eley-Rideal (ER)-type model on LA species, while leaving ER-type analogue on BA^--H⁺ species proper to reduce wet NO_X. Given hard-to-regulate strength/amount of -OH species and occasional association between E_NH3 and E_BARRIER, Ni₁V₂O₆ (Ni₁) was rationally chosen as a platform to isolate mono-dentate SO₃^2-/SO₄^2- species for use as BA^--H⁺ bonds via protonation to increase collision frequency (k’_APP,0) alongside with disclosure of advantages of SO₃^2-/SO₄^2--functionalized Ni₁V₂O₆ (Ni₁-S) over Ni₁ in reducing wet NO_X. Ni₁-S outperformed Ni₁ in achieving a larger BA^--H⁺ quantity (k’_APP,0↑), increasing H₂O tolerance, and elevating oxygen mobility, thus promoting NO_X reduction activity/consequences under SO₂-excluding gases. V₂O₅-WO₃ composite simulating a commercial catalyst could isolate mono-dentate SO₃^2-/SO₄^2- species and served as a control (V₂O₅-WO₃-S) for comparison. Ni₁-S was superior to V₂O₅-WO₃-S in evading ammonium (bi-)sulfate (AS/ABS) poison accumulation and expediting AS/ABS pyrolysis efficiency, thereby improving AS/ABS resistance under SO₂-including gases, while enhancing resistance against hydro-thermal aging.